Caption: West Nile Virus outbreak. Insecticide being sprayed to stop the spread of mosquitoes during an outbreak of West Nile Virus. West Nile Virus is an arbovirus (arthropod-borne virus) and is transmitted to humans and other mammals from infected birds through the bite of a mosquito vector. Symptoms can range from a mild fever to spontaneous bleeding of the skin and circulatory failure, which are often fatal. Photographed in Canada.